How do I make google maps always show where I am

I do not understand what you mean by this. Could you explain in more detail?
A guess is you want to use the LocationSensor and gps hardware to constant show your location as you move about. That is possible because the tool always knows where you are located.

App Inventor 2 has a Map control that uses OpenStreetMaps tiles, not Google Maps tiles to display a location on a map. Perhaps you could use the Map control to do what you want. There are plenty examples. Ramon's advice point you to one possible way to do it.